8 August, 1907.] Fiftli Convention, Chamber of Agriculture. 



493 



A criticism of the chemical composition of these soils reveals a series 

 of highly interesting facts and throws a flood of light on the question of 

 correct methods of cultivation and manuring. Fot example, the average 

 composition of the surface soils and subsoils is as follows: — 



These figures confirm a fact which has long been known to investigators 

 of Victorian soils, viz., that many of the northern subsoils are almost as 

 well furnished with plant foods as the surface soils. This plant food, 

 however, is of little service with the present shallow cultivation continued 

 year after year at the s.ame depth. What appears to be necessary is either 

 a system of cultivation which will stir the soil deeper without bringing the 

 subsoil to the surface or else the growth of tap rooted plants whose habit 

 of growth will permit them to find food at a depth of 8 or 10 inches from 

 the surface. This idea of deep cultivation is by no means new, and as al- 

 ready stated has formed part of the Department's experimental work in the 

 wheat districts during the past three years. The results are sufficiently far 

 advanced to say that in the northern and north-eastern plain districts this 

 mode of cultivation has shown sufficiently increased yields to justify the 

 extra cost of preparation. It will be noted in particular that the subsoils 

 are nearly as well supplied with .phosphoric acid as the surface soils, and 

 this Ftore' of plant food in the former should be unlocked by cultivation. 



It is astonishing to find what an enormous cash value per acre the plaiii 

 foods in the surfr.ce 30 inches of soil represent. Allowing a value of 

 9s. 6d. per unit for the nitrogen, 4s. for the phosphoric acid, and 5s. 6d. 

 for the potash, we can say that the average commercial value per acre of 

 the plant foods in the samples shown in the glass tubes is as follows: — 

 Nitrogen ... ... ... ^85 



Phosphoric acid ... ... ... 17 



Potash ... ... ... 37 



^139 



This is not, of course, the commercial value of an acre of land, but it 

 represents the potential wealth locked up in the soil which can only be 

 gradually drawn upon by intelligent working. There is little need to 

 pursue the subject further. The object of this paper will have been well 

 served if it succeeds in fixing the attention of the farmer more on the 

 cultivation of his soil, as being the most economical way of assisting it to 

 yield up its latent wealth. 



As the population of the State increa.ses and the ])rice of land rises 

 there is little doubt that a demand will be created for more knowledge of 

 the potential wealth of the soil. To meet that demand, it will, in my 

 opinion, be necessary for the Department I represent, to accumulate such 

 information bearing on the chemical and physical condition of the soils of 

 every district in the State. By this I do not mean to convey the idea that 

 anything in the nature of a comprehensive soil survey is necessary, but I 

 look forward tO' the time when every Agricultural Society and rural body 

 in the State will have a collection of the typical .soils of their district 



